Insecticide composition



Patented May 3,1927.

- UNITED STATES M11511 OFFICE.

, oscAn r. HEDENBURG AND DAVID s. PRATT, or PITTSBURGH, rENNsYLvANIm'As- SIGNORS TO THE TOLEDO REX SPRAY TION OF OHIO.

No Drawing. Application filed Jul 1,

This invention relates to improved insecti-' cide compositionscontaining lead arsenate and a defiocculating agent or agents, saidcompositions being readily suspendable in water and having improvedspreading, covering and adhesive qualities and forming an adherent dryfilm resistant to the erosive action of'water.

Lead arsen'ate insecticides have heretofore been made which weresuspendablein water, but such insecticides have all, so far as we areaware, been deficient in spreading, covering and adhesive qualities. Asa result of these defects, the particles of the lead arsenate tend toaggregate together and to become localized in groups upon surfaces towhich the insecticide isapplied, so that parts of the surfaces will havean excess of lead.

arsenate while other parts will be substantially free from it. Moreover,according to our observation, where the par icles thus tend to aggregatetogether and to thus become localized, the insecticide doesnot adherewell to the surfaces and can be readily 7 washed away, as by the actionof rain.

The improvedinsecticide compositions of the present invention aresubstantially free fromthe defects above mentioned. They can be readilysuspended and maintained in suspension in water, and they have improvedspreading and covering properties, so that they can be readily spreadout over the surfaces with substantial uniformity. The compositions,moreover, have improved adhesive ualities so that, when applied to thesuraces, the particles are relatively diflicult to remove, and areresistant to removal by washing, as by the actionof rain. According tothe present invention, lead arsenate, which may be produced by any '4suitable method of production, is compounded with a small amount of-adeflocculating "agent, such as gum arabic, which has-the property offorming thick,viscous solutions whichcharacterize hydrophilic oremulsoid colloids of which gum arabic is an example. The lead arsenatemay be either the normal lead arsenate (containing about AS205),

or. it may be the acid lead ar'senate (contain- COMPANY, OF TOLEDO,OHIO, A CORBORA- INSEOTIOIDE COMPOSITION.

1919. Serial No. 307,985.

ing about 32% to 33% AS205) and may be produced in any suitable mannerwhich will give particles or crystals of the lead arsearsenate; or bythe action of arsenic acid" upon an aqueous suspension of lead oxldecontaining a small amount of acid, such as nitric or acetic acid. M

The lead arsenate is, however, preferably and advantageously produced bythe gradual and regulated addition of a solution of arsenic acid orars'enic oxide to asuspension of fumed lead oxide in water heated toabout 70 to 100 0., and continually stirred during the reaction, as morefully set forth in our Patent No. 1,344,035, granted June 22, 1920. Thelead oxide which we have found particularly welladapted for use is theyellow fumed or sublimed lead oxide or litharge, but other suitablefinely divided forms of lead oxide may be similarly employed, forexample, air floated lead oxide.-- Either the normal lead arsenate orthe acid lead arsenate can be produced, depending upon the amount ofarsenic acid added, as will be readily understood. This method ofproduction of lead arsenate has, among others; the

advantages of economy of manufacture, substantial freedom fromelectrolytes in the;

product, and slightly larger yields as compared with processes in whichan acid, which will act as a solvent of thelead arsenate, is employed.

In the production of the novel insecticide compositions of the presentinvention, the lead arsenate, which may be either the normal arsenate orthe acid arsenate, or a mix: ture of both in any desired proportions,may be compounded with different defiocculating agents.

In preparation the lead arsenate may be filtered from the accompanyingliquor in the filter press, the filter cake dried, and

ground, for example, in a SchutzONeill mill and then thoroughly mixedwith about 1% of powdered gum arabic. The insecticide is thus obtainedin powder form and is available for use or for storage or shipment. Itmay thus be placed in suspension in water and applied as a spray in thecustomary manner. Similarly, the new insecticide composition is valuablefor use as a dusting powder because of its superior adhesive andspreading qualities, especiallyafter moistening by dew or rain.

So also the insecticide composition can be produced in paste form, forexample, in the form of a 50% paste of lead arsenate, by intimatelymixing and incorporating the gum arabic with the filter cake containingthe proper amount of water. A corresponding amount of gum arabic can beused for this purpose, i. e., about 1% of the weight of the leadarsenate. The incorporation of the gum arabic, and the production of thepaste,

can be effected in any suitable apparatus, as in an appropriate kneadingor mixing machine.

The employment of lead Jarsenate produced in the manner above describedand as more fully set forth in our Patent No. 1,344,035, has theadvantage that the lead arsenate is free from electrolytes such asnitric acid or soluble lead salts, which, if

present in objectionable amount. mightinterfere with the production ofsuspensions of the desired composition in the desired state ofdispersion or defiocculation. Any

suitable form of lead arsenate can, however,

be similarly employed in the production of the novel composition of thepresent invention, provided it does not contain impurities or admixtureswhich interferewith the desired action of the deflocculating agents.Commercial leadarsenate deficient in suspensionand adhesive power canthus be converted into a composition'with immensely improved suspensionand adhesive power; Nevertheless, as above pointed, out, we considerlead arsenate produced as above dethe improved spreading, coveringandadhe-.

sive qualities above referred to, and, when examined under themicroscope, shows the particles in a dispersed state, distributed henthe insecticide composition of the terraces with substantial uniformity;whereas, insecticides heretofore known, in as far as we haveinvestigated them, show the particles aggregated together in the form ofgroups when examined under the microscope. It is due to this dispersedor defiocculated condition, aswe believe, that the composition can 4 beapplied with uniformity, for example, to foliage, so that it will beuniformly spread out over the leaves and so that different '3' parts ofthe leaf will be provided with their proportionate particle or particlesof the insecticide.

A comparison of the novel composition of the present invention withinsecticides previously known shows that the compositions of the presentinvention have markedly superior adhesive qualities. It has thus beenfound that when the composition is uniformly distributed over a leaf, itis not readily washed off, whereas with insecticides pre-:

.viously known the insecticide is not only unevenly distributed over theleaf, but is more easily washed off, even by rain. The insecticidecompositions of the present invention accordingly retain theireffectiveness over longer periods of time, and particu-- larly afterperiods of rain which will remove to a serious degree lead arsenateinsecticides heretofore known. These advantages of the present inventionare cumulative. in that the insecticides of the present inventionprovide increased protection to vegetation, due to their evendistribution and to the freedom from aggregation and uncovered spacesbearing no insecticides, and to the prolonged life or period ofusefulness during which the insecticides remain affixed to the foliage.The improved insecticides of the present invention can be distinguishedfrom the lead 105 arsenate used in their production (which is free fromany admixture with a defiocculating agent), and from all lead arsenatesheretofore known, in so far as we are aware, by the followingcomparative test. Two grams ill? of the new insecticide composition andtwo "grams of the old lead arsenate, respectively,

are suspended in cc. of water and immediately, after thorough agitation,applied to clean glass plates to'form a continuousla'yer thereon. Afterstanding'one minute the excess is shaken off and the plates dried. Therewill then be a substantially continuous and even coating of the newcomposition, while the old 'arsenate will present an uneven anddiscontinuous coating. The plates are then similarly held in rapidlyrunning water-for 7 half a minute and then dried. There will still be asubstantially continuous and even coating of the new composition,substantially the same in appearance as before, while a large amount ofthe old lead arsena'te will be washed off, and that remaining willpresentv a pronounced unevenness and lack of continuity. Even whensubmitted to a violent stream of water it has been found that a nearlycontinuous coating of the new compositlon remains.

. When the layer of the suspension of the new composition is spread onthe glass plate, as above described, it runs evenly over the glass andpresents a uniform milky appearance, whereas the suspension of the oldlead arsenate, when similarly spread over a glass plate, shows apronounced tendency of the particles to aggregate and to distributethemselves unevenly.

- The radically improved suspension properties of the new compositionwill be apparent from the following tables, giving the results ofcomparative suspension tests made with dry lead arsenates and with theSame lead arsenates compounded with 1.25% o]? gum arabic, mixed on a drybasis. The lead arsenate marked No. 1 was produced in accordance withthe process of-our Patent No. 1,344,035, as above described. The leadarsenates marked Nos. 2 to 5 were commercial forms of lead arsenate uponthe market. These tests were made by suspending ('3 grams of the drylead arsenate, or ofthe composition of lead arsena'te and gum arabie, atordinary temperatures, in 250 cc. of water in a cylinder of about 1inches diameter,

having a gradua-ted'scale on its side, ranging from 250 cc. at the topto 0 cc. at the bottom. The suspensions were shaken at'the same time andobservations made at the ends of the periods indicated, as shown in thetables. 1

' The figures given in Table I are the lines of separation of thesuspension and the clear, water above, that .is,'; the extent to whichthe suspension has settled from the "250 cc. mark at the ends of therespective periods of time. 1

Tin 1m No. I. Lead. cram ate without-gum arabic.

, Time. No. 1. No. 2. No; '3. No. 4. No. 5.

Ce. 01'. 0c. Cc. Cc.

190 130 195 190 q .175 11 0 46 .110 64 '33 72 40 55 39 28 44 30 l 37 3626 41 '27 .33 33 24 38 25 31' 30 2a 35 g 24 as 27 .22 33 24 27 26 22 3323 27 26 22 33 23 27 25 2l 31 23 27 25 21' 31 23, 27 25 21 '31 $3 27 InTable No. II there are two notations. The figures preceded by, the wordBulk in- 'dicatethe volume, at the bottom of the cylin der, of theheavier solid particles, which settled out and were more or less clearlydefined from the still milky liquid above containing the finerparticles. The figures procede'd by the words Clear to indicate theextent to whiclr the finely divided or de- -a more or has 'fiocculatedmaterial settled out leaving a clear liquid above.

TABLE No. II.l.ea d arsena'te with g-u-m araln'c.

Time. No.1. No.2. No.3. No.4. No.5.

minut'genn cc. 350 cc 250 cc.

m1nues 50 50 5 ni iutes.-- 23 cc 13 cc 6 cc. 10 minutes .24 14 7 15minutes 22 14 7 20 minutes," I M 8 Buik.- s '11 '20 "14''" 9 (318 to m249 249 u 12 19 1s 11 to 249 24g 246 249 24s e 1 10 16 12 "igle z t 21g249 245 247 244 u 14 1e 1e 14 \Clearto-.. 246 248 24a 245 238 [Bulk e 14va0- 11 14 19 to--. 24% 248 233 243 235 u 1 5 11 15 19-11mm"llcilelfigto... 2 inv 206 222 200 1 u 5 2o 17 15 emma)... 215 238 200'2 14 186 arsenates of Tablej'N'o. I Elie lcald arsenates of Table'No. Isettle. comp at'i'vely rapidly. The compositions (of Tab 'II remain insuspension for rolong riods of time, and the heavierparticles,

. isti ct settle out much more-slowl. andlin muchless amount tha ddth'dlead a'r's'enates of Table No. I. 1 Even 'iterffseveral-hours timethere still remain ve .ylconsid the com osi ns suspension in the formofa mil suspensioxtwith no sharp line of demarcation fromftlie clearwater above.

Moreover, [from a comparison of the differentcomposition'soff:Table No.II, it will .be seen that the composition'indicated by No. ,I: hasmarkedly superior. "suspension proper-' 'ti'es't" i retains nearlyall insuspension withoutthe "settling .butfof any "considerable amount ofheavierjj'particles, while the amount so set fled-out" does not,materially increase after the first ten minutes. This composition,accordingly, can .be'used to" advantage even without :agit-ation'of thecomposition in the spray tank, during its use as a spray.

hose, of the other. compositions, and

all settle out in r nevertheless erable proportions of Theinsecticidesof thepresent invention may contain compoundedorincorporated therewith, other insecticide ingredients, for

example, lime-sulphur insecticides and fungicides, such as are commonlyemployedin the art, provided thes.'-"added in redients-do not destroy orprejudice the desired -defioc-- culating action of'the deflocc'ulatingagent or agents'andthe resulting defiocculated or prepared.Thelime-sulphur products may thus, for example, be prepared inaccordance and possibly lead sulpho-arsenate.

with the procedure set forthin the Patent No. 1,336,957, granted April13, 1920.

I When lead arsenate is used with lime-sulphur solution, for example, ina ratio of 50 gallons of water, one and a quartergallous of 32 Baumlime-sulphur solution and one pound of lead arsenate powder, twoimportant' disadvantages are commonly encountered. Ordinary leadarsenate tends to decompose. limessulphur solution rapidly with theformation of black lead sulphide At the same time, the-suspensionproperties of the lead arsenate are largely destroyed. The

new lead arsenafecompositious of the presentfinventiom'being largelyfree from electrolytes and containing a colloidal deflocculating agent,such as gum arabic, has much les tendency to react with lime-sulphurwith the resulting formation of lead sulphide and the removal of activecalcium polysulphides.

- This characteristic difference is clearly shown by noting'the relativerates at which darkening occurs when'ordinary lead arsenate, compoundedwith lime-sulphur, is compared with the new lead arsenate compositionsimilarly treated. It should be understood that darkening willinvariably occur to a greater or less extent in every case, but thistendency will be much less marked with the new comeaaaee' positions ofthe present invention. Under the above conditions the improvedsuspension power of the new lead arsenate and its adhesive qualities,after drying, are retained.

We claim:

1. Anjnsecticide composition comprising lead arsenate and an emulsoidcolloid, said composition, when used in admixture with lime-sulfur as aspray, being readily suspeudable in water, and the resulting spray,after drying, forming an adherent film resistant to the erosive actionof water.

2. An insecticide composition comprising lead arsenate having arelatively small proportion of gum arabic incorporated therewith andadapted when said composition is dcposifed from a liquid suspension upona surface to provide a substantially continuous and adhering coating ofsaid composition upon said surface.

3. An insecticide composition comprising lead arsenate substantiallyfree from electrolytes and having a relatively small proporlion of gumarabic incorporated therewith,

said composition being adapted, when deposited from a liquid suspensionupon a surface, to provide a substantially continuous and adheringcoating upon said surface.

4. An insecticide composition comprising lead arsenate, a relativelysmall proportion of gum arabic', and lime-sulfur constituents, saidcomposition having superior suspension qualities and forming, when usedas a spray, an adherent dry film resistant to the erosive action ofwater. I

In testimony whereof we hereunto aiiix our signatures.

OSCAR F. HEDENBURG. DAVID S. PRATT.

